Networks enable computers and other devices to communicate. For example, networks can carry data representing video, audio, e-mail, and so forth. Typically, data sent across a network is divided into smaller messages known as packets. By analogy, a packet is much like an envelope you drop in a mailbox. A packet typically includes “payload” and a “header”. The packet's “payload” is analogous to the letter inside the envelope. The packet's “header” is much like the information written on the envelope itself. The header can include information to help network devices handle the packet appropriately. For example, the header can include an address that identifies the packet's destination. A given packet may travel across many network nodes (e.g., “routers”, “bridges” and “switches”) before reaching its destination.
FIG. 1 illustrates an example of components forming a network node. As shown, the node includes a network interface that connects a processor system to a network (shown as a cloud). Typically, an intermediate node, such as a router, will include many different network interfaces. As shown, the interface carries packets traveling between the processor system and the network.
Network interfaces often compile statistics on their operation such as the number of packets or bytes received or transmitted. For instance, as shown, the interface updates the statistics for packets received (packet “a”) and sent (e.g., packet “b”).